Lightweight polymer pellet

ABSTRACT

A lightweight pellet ( 10 ) is provided having an exterior shell ( 11 ) made of an already-expanded polymer material. Each pellet ( 10 ) has a specific gravity of about 0.01 to about 0.3 and has an average size of about 0.01 mm to about 6 mm. A plurality of the pellets ( 10 ) can be used to make free-flowing materials, liquid carrier compositions, solidified pods, coating layers, and/or masonry units.

RELATED APPLICATION

This application claims priority under 35 USC §119(e) to U.S. Provisional Patent Application No. 61/591,254 filed on Jan. 26, 2012. The entire disclosure of this provisional application is hereby incorporated by reference.

BACKGROUND

A microsphere, or pellet, can be made by encasing a liquid droplet in a polymer. The droplet can comprise a blowing agent, nucleating agent, or an expansion agent that, when heated, expands the polymer casing to several times the original droplet diameter or forms the polymer shell. Upon cooling, the polymer remains expanded to form an exterior shell, and the agent condenses back to liquid to thereby create a substantially hollow interior core.

SUMMARY

A lightweight pellet is provided having a specific gravity of about 0.01 to about 0.3 and having an average size of about 0.01 mm to about 6 mm. The pellet has an already-expanded shell and substantially hollow interior core. A plurality of the pellets can be incorporated into free-flowing materials, liquid carriers, solidified binders, pods, coatings, and/or masonry units.

DRAWINGS

FIGS. 1A-1C show a lightweight pellet 10.

FIGS. 2A-2C show a material 20 comprising free-flowing pellets.

FIG. 3 shows a material 30 comprising a liquid carrier and pellets dispersed therein.

FIGS. 4A-4C show a cavity-occupying pod 40 comprising a solidified binder with pellets dispersed therein.

FIGS. 5A-5C show a coating 50 comprising a solidified binder with the pellets dispersed therein.

FIG. 6 shows a masonry unit 60 with pellets disposed therein.

DESCRIPTION

Referring now to the drawings, and initially to FIGS. 1A-1C, a pellet 10 is shown which comprises an exterior shell 11 completely enclosing an interior core 12. As shown in FIG. 1B, the shell 11 can comprise a wall 13 which incorporates the pellet's outer surface 14. Alternatively, as shown in FIG. 1C, the shell 11 can additionally comprise a coating 15 surrounding its wall 13, and this coating 15 can incorporate the pellet's outer surface 14. In either or any case, the pellet 10 preferably has a specific gravity between 0.01 and 0.30, and/or a bulk density of 1 to 18 lb/ft³ (16 to 300 kg/m³).

The pellet size (e.g., its diameter D10) and/or the shell size (e.g., its diameter D11) can be between about 0.01 mm and about 6 mm. The shell's thickness T11 is determined by the difference between its diameter and that of the interior core 12. This thickness T11 can be at least about 10%, at least about 20%, and/or at least about 30% of the shell's diameter D11. And the shell thickness T11 will usually be significantly less than the shell's diameter D11 (e.g., significantly less than 50%, significantly less than 30%).

The exterior shell 11 can comprise a thermally expanded polymer which is typically thermoset and/or which has a glass transition temperature significantly greater than those of the expected installation or usage conditions.

If the pre-expansion shell structure surrounds an expansion/blowing agent, and the shell 11 is impervious to this agent, the interior core 12 may still contain this agent in a condensed condition. If the expanded shell material allows dissipation of the blowing agent, the interior core 12 may contain only vented gas (e.g., air, oxygen, carbon dioxide, nitrogen, etc.) and it will be void of solid or liquid contents. Alternatively, the core 12 could be lightweight foam or other lightweight material such as a multicellular closed foam cell bead.

In some applications, it will be important for the pellet 10 to be nonporous with respect to water or other liquids. When the shell's wall 13 is impervious to the blowing agent, it will often also be impervious to moisture or other liquid vapors. If so, a coating-less construction may be possible, with wall 13 incorporating the pellet's outer surface 14 as shown in FIG. 1B. When the shell's wall 13 is designed to allow the permeability of the expansion/blowing agent, the coating 15 may be necessary to seal the venting openings. And even with a moisture-impervious wall 13, a coating 15 or other additional polymer layer can be provided for other reasons, such as rigidity, flowability, heat resistance, chemical resistance, surface properties, and/or resin compatibility.

Referring to FIGS. 2A-2C, a material 20 can comprise a plurality of free-flowing pellets 10. The material 20 can be poured, pumped, or blown into a cavity 22 (e.g., under a floor, behind a wall, over a ceiling, into a crawl space, etc.) at a construction site for insulation or other purposes.

Referring to FIG. 3, a material 30 can comprise a liquid carrier 31 with a plurality of pellets 10 dispersed therein. When disposed in the carrier 31, the pellets 10 remain substantially the same size, shape, and specific gravity. The carrier composition and/or the material viscosity can depend upon its intended use and/or desired functions. In most instances, the pellets 10 can collectively account for a significant percent of the material volume (e.g., at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90% and/or at least 95%).

Referring to FIG. 4A-4C, the material 30 can be used to make a pod 40 comprising a solidified carrier 41 with pellets 10 dispersed therein. The pod 40 can be made by fluidly introducing (e.g., pouring or pumping) the material 30 into a cavity 42. The volume of the material 30 introduced into the cavity 42 can be equal to the pod's volume whereby an installer can visually confirm filling of the cavity 42. And the material/pod is preferably dimensionally stable after installation with its volume remaining the same (e.g., within 5%, within 4%, within 3%, within 2%, within 1%, etc.) for many years (e.g., at least 5 years, at least 10 years, at least 20 years, etc.). In this manner, there will be essentially no sewing, shrinkage, expanding, swelling, sagging, or other undesirable deformations at the construction site. The liquid carrier 31 and the binder 41 can comprise a polymer (e.g. resins, latexes, urethanes, silicones, epoxies, acrylics, etc.) that is liquid in an uncured state and readily solidify once cured.

Referring to FIGS. 5A-5C, the material 30 can be used to make a coating layer 50 comprising a solidified binder 51 and pellets 10 dispersed therein. The layer 50 resides on a structural surface 52 and it can be sprayed, troweled, brushed, or otherwise applied thereto. The layer-making material 30 can be formulated so as to have a viscosity that allows it be readily applied to the substrate surface 52 by spray coating, dip coating, extrusion coating, flow coating, spread coating, brush coating, pouring, or gravity flow methods. Again, the liquid carrier 31 and the binder 51 can comprise a polymer (e.g. resins, latexes, urethanes, silicones, epoxies, acrylics, etc.) that is liquid in an uncured state and readily solidifies once cured.

Additionally or alternatively, the pellets 10 can be precoated with binder and/or resin that can be cured to solidify the material 30 or otherwise form a rigid composition. Such curing could be accomplished, for example, by oxidation or ambient cure, two-part reactive systems, catalyzed cure, radiation, ultraviolet, or electrobeam procedures. Precoated pellets 10 could be preferably formulated so as to be easily pumped, poured, or conveyed until applied or installed for ultimate use. For example, they could be nontacky in a pre-cured condition and bind together in their post-cured condition.

Referring to FIG. 6, the material 30 can be used to make a masonry unit 60 having a binder 61 and a plurality of pellets 10 dispersed therein. In this case, the carrier 31 could comprise a mixture of cement and aggregate, as well as liquid, resin, binder or adhesive.

The pellets 10, the free-flowing material 20, the carrier material 30, the pod 40, the layer 50, and/or the masonry unit 60 can be adapted to provide thermal insulation (e.g., they can have an R value of at least 2.0 or an RSI value of at least 0.30) and/or sound attenuation (e.g., they can have an STC factor of at least 30). And other agents can be incorporated to provide features such as flame retarding, smoke suppressing, electrical dissipation/conductivity, and/or organism killing (e.g., biocide, fungicide, insecticide, mildewcide, bactericide, rodentcide, etc.).

Although the pellets 10, the free-flowing material 20, the liquid-carrier material 30, the pod 40, the layer 50, and/or the masonry structure 60 have been have been shown and described as having certain forms and fabrications, such portrayals are not quintessential and represent only some of the possible adaptations of the claimed characteristics. Other obvious, equivalent, and/or otherwise akin embodiments could instead be created using the same or analogous attributes.

It will also be obvious to one skilled in the art that this material can be advantageously applied into or onto equipment housings (HVAC units, transformers, electrical switchgear, etc.), industrial storage or mixing tanks, pipelines and process lines, aircraft, watercraft, motor vehicles, bathtubs, swimming pools, spas and the like. 

1. A pellet having a specific gravity of about 0.01 to about 0.3 and having an average size of about 0.01 mm to about 6 mm; wherein the pellet comprises an exterior shell completely enclosing an interior core; and wherein the exterior shell is made of an already-expanded thermoplastic material.
 2. A pellet as set forth in claim 1, wherein the interior core has a small amount of liquid content.
 3. A pellet as set forth in claim 1, wherein the interior core contains an expansion agent.
 4. A pellet as set forth in claim 3, wherein the exterior shell is impervious with respect to the liquid content.
 5. A pellet as set forth in claim 1, wherein the exterior shell comprises a wall which incorporates the pellet's outer surface.
 6. A pellet as set forth in claim 1, wherein the shell comprises a wall and coating surrounding the wall, and wherein the coating incorporates the pellet's outer surface.
 7. A pellet as set forth in claim 1, wherein the thickness of the exterior shell is at least 5% of the shell's diameter and/or wherein the thickness of the shell is significantly less than 50% of the shell's diameter.
 8. A free-flowing material comprising a plurality of the pellets set forth in claim
 1. 9. A free-flowing material as set forth in claim 8, additionally comprising a liquid carrier in which the pellets are dispersed.
 10. A free-flowing material as set forth in claim 9, wherein the pellets remain substantially the same size, shape, and specific density in the liquid carrier.
 11. A free-flowing material as set forth in claim 8, wherein the pellets are precoated with a binder adapted to solidify the material into a rigid composition.
 12. A free-flowing material as set forth in claim 11, wherein the binder is adapted to be cured to solidify the material into a rigid composition.
 13. A pod made by fluidly introducing the free-flowing material of claim 8 into a cavity and allowing the material to solidify, wherein the volume of material introduced into the cavity is substantially equal to the pod volume.
 14. A coating layer made by applying the free-flowing material of claim 8 onto a substrate surface and allowing the material to solidify.
 15. A pod comprising a plurality of the pellets set forth in claim 1, dispersed in a solidified binder, wherein the pod has volume which remains within about 5% of its installation volume for at least 5 years.
 16. A pod as set forth in claim 15, having an R value of at least 2.0 and/or having an STC factor of at least
 30. 17. A coating layer comprising a plurality of the pellets set forth in claim 1 dispersed in a solid binder.
 18. A masonry unit comprising a plurality of the pellets set forth in claim 1, and a hardened cement mixture comprising cement, an aggregate, and/or resin, binder or adhesive systems. 